1. Field of the Invention
The present invention relates generally to in situ detection of the strain levels imposed on components, and more particularly to an apparatus for detecting the strain levels imposed on a circuit board.
2. Description of the Related Art
Many components (e.g., a circuit board or printed wire board) are exposed to high strain levels caused by normal and unanticipated movements of the components during use. For example, these components may be used on aircrafts, automobiles, vehicles, home appliances, spacecrafts and various electromechanical (EM) devices. The high strain levels cause the components to crack, break or fail to perform. That is, after a finite amount of time, the components may crack, break or fail causing the system to fail or malfunction. For example, high strain levels produced on a circuit board may cause the electronic components on the circuit board to malfunction.
Some devices have been used to detect the presence of strain levels imposed on the components. For example, accelerometers have been used to detect the presence of strain levels. In one configuration, an accelerometer may be placed on a housing that contains the components to measure the strain levels imposed on the components. Receiving these measurements, however, does not provide a very accurate measurement because the accelerometer is measuring the movement of the housing rather than the movement of the components. Therefore, an accurate measurement may not be obtained unless the accelerometer is placed on each system component within the housing, which is costly, inefficient and impractical.
A sensor device can be used to detect structural defects in a work piece by monitoring the electrical continuity of thin crack wires deposited on or within the work piece. The sensor device includes a discontinuity sensor that applies a voltage to one end of the crack wire and monitors the voltage level at the other end of the crack wire to determine if the crack wire is broken, thereby indicating the presence of a crack, delamination or other defect. One drawback of this sensor device is that the work piece must include many thin crack wires in order to detect damage to different parts of the work piece.
Thus, it should be appreciated that there is a need for providing economical and effective real-time data on the strain levels imposed on circuit boards in use. The present invention fulfills this need as well as others.